<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
    <style type="text/css">
        body, html,#allmap {width: 100%;height: 100%;overflow: hidden;margin:0;font-family:"微软雅黑";}
    </style>
    <script type="text/javascript" src="http://api.map.baidu.com/api?v=2.0&ak=XPFOXZxZCZwuGqFninoYGjkPiXhPt5uu"></script>
    <script type="text/javascript" src="http://api.map.baidu.com/library/RectangleZoom/1.2/src/RectangleZoom_min.js"></script>
    <title>鼠标拉框放大地图</title>
</head>
<body>
<div id="allmap"></div>
</body>
</html>
<script type="text/javascript">
    // 百度地图API功能
    var map = new BMap.Map("allmap");
    map.centerAndZoom("重庆",12);
    var myDrag = new BMapLib.RectangleZoom(map, {
        followText: "拖拽鼠标进行操作"
    });
    myDrag.open();  //开启拉框放大
    //myDrag.close();  //关闭拉框放大
</script>
